Plasma Nonesterified Fatty Acids Research Articles

The SGLT2 Inhibitor Dapagliflozin Increases the Oxidation of Ingested Fatty Acids to Ketones in Type 2 Diabetes.

To investigate the mechanism for increased ketogenesis following treatment with the SGLT2 inhibitor dapagliflozin in people with type 2 diabetes. The design was a double-blind, placebo-controlled, crossover study with a 4-week washout period. Participants received dapagliflozin or placebo in random order for 4 weeks. After each treatment, they ingested 30 mL of olive oil containing [U-13C]palmitate to measure ketogenesis, with blood sampling for 480 min. Stable isotopes of glucose and glycerol were infused to measure glucose flux and lipolysis, respectively, at 450-480 min. Glucose excretion rate was higher and peripheral glucose uptake lower with dapagliflozin than placebo. Plasma β-hydroxybutyrate (BOHB) concentrations and [13C2]BOHB concentrations were higher and glucose concentrations lower with dapagliflozin than placebo. Nonesterified fatty acids (NEFAs) were higher with dapagliflozin at 300 and 420 min, but lipolysis at 450-480 min was not different. Triacylglycerol at all time points and endogenous glucose production rate at 450-480 min were not different between treatments. The increase in ketone enrichment from the ingested palmitic acid tracer suggests that meal-derived fatty acids contribute to the increase in ketones during treatment with dapagliflozin. The increase in BOHB concentration with dapagliflozin occurred with only minimal changes in plasma NEFA concentration and no change in lipolysis. This finding suggests a metabolic switch to increase ketogenesis within the liver.

Effect of different dietary regimens at dry-off on performance, metabolism, and immune system in dairy cows

Concentrate withdrawal and feed restriction are commonly used to reduce milk production and to facilitate dry-off, but may impair immune function in dairy cows. We investigated the effect of feed rations providing different amounts of nutrients in combination with feed restriction on performance, endocrine, and metabolic responses, as well as on leukocyte function before and after abrupt dry-off. Forty-three cows were studied from d 12 before until d 6 after dry-off (56 d before scheduled calving). Cows were fed experimental concentrates rich in crude protein (nitrogenic, n = 14), glucogenic precursors (glucogenic, n = 14), or lipids (lipogenic, n = 15). On d 3 before dry-off, total feed allowance was restricted to 50% in half of the animals of each dietary group, whereas feed allowance remained unchanged in the other animals. Performance parameters (milk yield, milk composition, and dry matter intake) were recorded, and daily blood and milk samples were taken and analyzed for various metabolic and endocrine parameters. Additionally, activity and mRNA abundance of several genes in leukocytes were measured at selected time points before and after feed restriction and dry-off, respectively. Feed restriction immediately resulted in a negative energy balance and decreased milk production. Concomitantly, concentrations of nonesterified fatty acids increased, whereas insulin, insulin-like growth factor-1, and glucagon decreased. After dry-off, energy balance turned positive and plasma nonesterified fatty acids decreased. Plasma glucose, insulin, and insulin-like growth factor-1 concentrations increased in all groups after dry-off. Glucose, insulin, and glucagon concentrations in plasma were higher in nonrestricted compared with restricted animals after dry-off. The experimental concentrate types marginally affected the investigated metabolic and endocrine factors, with the exception of elevated milk and plasma urea concentrations in cows fed the nitrogenic concentrate. Chemotactic and phagocytic activity of leukocytes were not affected by diets, feed restriction, or dry-off. Likewise, blood leukocyte mRNA abundance encoding for tumor necrosis factor α (TNF), heat shock protein family A (HSP70), and the glucose transporters (GLUT) 1 and 3 remained unchanged throughout the study period. Overall, the short-term negative energy balance induced by feed restriction was temporarily accompanied by metabolic adaptations, but did not alter the studied factors related to the immune system. Metabolic and endocrine adaptations supporting milk synthesis were continued during the first days after dry-off despite cessation of milking. Thus, the abrupt dry-off resulted in a short-term increase of glucose and triglyceride concentrations, with a delayed endocrine response to re-establish nutrient homeostasis in blood.

How to approach the resilience of livestock exposed to environmental challenges? Quantification of individual response and recovery by means of differential calculus

This work was originated from the need to study how animals individually react to environmental challenges. Common practical constraints in research protocols often lead to data collected at frequencies that are not high enough to capture the dynamics of animal responses. One approach to deal with that issue is to transform discrete empirical time series into continuous functions from which several descriptors can be extracted to characterise the response. A method for the extraction of smoothed functions from milk yield (MY) time series has been published before for dairy cows. This method was applied to detect challenges a posteriori. In this paper, we present an adaptation of this differential smoothing methodology, for the case when the environmental challenge is known a priori. This is advantageous because it allows for a more detailed characterisation of the response. Full description of the methodology is presented, where operations from differential calculus are applied to the smoothed functions to extract 23 descriptors that characterise the shape, dynamics and delay of individual responses to a single known challenge. We present examples of the application of the algorithm to individual time series of MY and plasma non-esterified fatty acid concentrations from suckling cows exposed to nutritional challenges that are known a priori. We propose a selection strategy for the smoothing coefficient (λ) based on the optimisation between noise reduction and output stability. If applied to groups of individuals that are sufficiently large, this methodology could provide information to help discriminating animals based on how they respond to the environmental challenges. This methodology may be used to develop decision-making tools for the selection of resilient individuals aiming at improving robustness and performance.

Rubicon deficiency exacerbates fasting-induced hepatic steatosis

Abstract Objective: Rubicon is an inhibitory interacting protein of the autophagy-related protein Uvrag. We previously showed that Rubicon deficiency promotes autophagic flux in vivo and that autophagy can degrade lipid droplets. This study aimed to investigate the effects of Rubicon deficiency on fasting-induced hepatic steatosis. Methods: Two-month-old wild-type (WT) and Rubicon-deficient mice were subjected to feeding or fasting for 24 hours to induce hepatic steatosis. The distribution of liver lipid droplets was revealed by oil red O staining. Hepatic and plasma triglyceride, non-esterified fatty acid (NEFA), and cholesterol levels were detected using commercially available kits. Real-time reverse transcriptase-polymerase chain reaction was performed to analyze the mRNA expression of genes related to lipid metabolism in the liver. Western blot was conducted to assess autophagy-related protein levels in the liver. The animal experiments were approved by the Institutional Animal Care and Use Committee at Shanghai Jiao Tong University, China. Results: We showed that under fasting conditions, Rubicon-deficient mice had more lipid droplets in the liver than WT controls. Consistent with these results, the hepatic triglyceride, NEFA, and cholesterol levels in fasted Rubicon-deficient mice were significantly higher than those of fasted WT controls. The levels of SREBP-1, a key regulator of lipid synthesis, were significantly lower in livers from fasted WT mice than those of fed WT mice. However, the decrease in SREBP-1 in fasted mice was attenuated by Rubicon deficiency. Western blot analysis demonstrated that the fasting-induced increase in autophagic flux was amplified by Rubicon deficiency. Finally, we showed that Rubicon deficiency in mice led to elevated plasma triglyceride and NEFA acid levels under fasting conditions. Conclusion: Rubicon deficiency exacerbates fasting-induced hepatic steatosis in mice.

Associations between peripartum lying and activity behaviour and blood non-esterified fatty acids and β-hydroxybutyrate in grazing dairy cows

During early lactation, most dairy cows experience negative energy balance (NEB). Failure to cope with this NEB, however, can place cows at greater risk of developing metabolic disease. Our objective was to characterise, retrospectively, lying behaviour and activity of grazing dairy cows grouped according to blood non-esterified fatty acids (NEFAs) and β-hydroxybutyrate (BHB) as indicators of postpartum metabolic state. Blood was sampled weekly for up to 4 weeks precalving, on the day of calving (day 0), daily between 1 and 4 days postcalving, and then at least weekly between week 1 and week 5 postcalving for analysis of plasma NEFAs and BHB concentrations. Two hundred and forty-four multiparous Holstein-Friesian and Holstein-Friesian × Jersey cows were classified into one of three metabolic status groups based on maximum blood NEFAs and BHB concentrations during week 1 and 2 postcalving. A cow was classified as having either: (1) low NEFAs and low BHB (Lo–Lo; n = 78), when all blood samples were <1.0 mmol/L for NEFAs and ≤1.0 mmol/L for BHB during the first 2 weeks postcalving; (2) high NEFAs and low BHB (Hi–Lo; n = 134), when blood NEFAs were ≥1.0 mmol/L and blood BHB was ≤1.0 mmol/L at the same sampling time point during the first 2 weeks postcalving; or (3) high NEFAs and high BHB (Hi–Hi; n = 32), when blood NEFAs were ≥1.0 mmol/L and blood BHB was ≥1.2 mmol/L at the same sampling time point during the first 2 weeks postcalving. Accelerometers (IceTag or IceQube devices; IceRobotics Ltd.) were used to monitor lying and activity behaviours peripartum (–21 to +35 days relative to calving). Changes in lying behaviour and activity occurred before the mean day that cows were classified Hi–Hi and Hi–Lo (2.2 and 3.5 d postcalving, respectively). Up to 3 weeks preceding calving, Hi–Hi cows were more active, had fewer daily lying bouts (LBs), and spent less time lying than Lo–Lo cows. In addition, Hi–Hi cows had fewer daily LBs and were less active up to 4 weeks postcalving than Lo–Lo cows, but these differences were biologically small. Groups of grazing cows classified as experiencing a more severe metabolic challenge behave differently up to 3 weeks precalving than their herdmates with lower blood NEFAs and BHB postcalving. These altered behaviours may allow identification of individual cows at risk of a metabolic challenge, but further research is required.

Modulation of Fecal Metabolites by Heat Stress and Diet, and Their Association with Inflammation and Leaky Gut Markers in Dairy Cows.

The analysis of fecal metabolite profiles could provide novel insights into the mechanisms underlying animal responses to environmental stressors and diet. We aimed to evaluate the effects of a 14-day heat stress period and of dietary mineral and vitamin supplementation under heat stress on fecal metabolite profiles and to investigate their associations with physiological markers of heat stress, leaky gut, and inflammation in lactating dairy cows. Twelve multiparous Holstein cows (42.2 ± 5.6 kg milk/d; 83.4 ± 27.1 DIM) were enrolled in an experiment in a split-plot design. The main plot was the level of dietary vitamin E and Se, as follows: (1) low (L-ESe; 20 IU/kg vitamin E, 0.3 ppm Se) or (2) high (H-ESe 200 IU/kg vitamin E, 1.2 ppm Se). Within each plot, six cows were randomly assigned to either (1) heat stress (HS; Total Humidity Index (THI): 82), (2) pair-feeding in thermoneutrality (TNPF; THI = 64), or (3) HS with vitamin D3 and Ca supplementation (HS+DCa; 1820 IU/kg and 1.5% Ca; THI: 82) in a replicated 3 × 3 Latin square design with 14-day periods and 7-day washouts. The concentrations of 94 metabolites were determined in fecal samples, including amino acids, fatty acids, biogenic amines, and vitamins. Relative to the L-ESe group, the H-ESe group increased α-tocopherol by threefold, whereas δ-tocopherol was decreased by 78% (PFDR < 0.01). Nevertheless, correlation analysis between α-tocopherol and all the others fecal metabolites or physiological heat stress measures did not show significant associations. No interactions between main plot and treatments were observed. Relative to TNPF, HS increased plasma tumor necrosis factor-alpha (TNF-α), plasma lipopolysaccharide-binding protein (LBP), milk somatic cell counts (SCC), respiratory rates, rectal temperatures, fecal tridecylic and myristic acids, vitamin B7, and retinol, whereas it decreased fecal amino acids such as histidine, methyl histidine, acetyl ornithine, and arginine (PFDR < 0.05). In contrast, HS+DCa increased fecal methyl histidine concentrations and reduced milk SCC, plasma TNF-α, and LBP, as well as rectal temperatures. Discriminant analysis revealed fecal histidine, taurine, acetyl ornithine, arginine, β-alanine, ornithine, butyric + iso-butyric acid, plasma non-esterified fatty acids, TNF-α, LBP, C-reactive protein, and milk SCC were predictive of HS. Several metabolites were predictive of HS+DCa, although only tryptophan was discriminant relative to HS. In conclusion, both heat stress and the supplementation of vitamin D3 and Ca can influence the fecal metabolome of dairy cows experiencing heat stress, independently of dietary levels of vitamin E and Se. Our results suggest that some fecal metabolites are well associated with physiological measures of heat stress and may thus provide insights into the gut-level changes taking place under heat stress in dairy cows.

The effect of dietary rumen-protected trans-10,cis-12 conjugated linoleic acid or a milk fat-depressing diet on energy metabolism, inflammation, and oxidative stress of dairy cows in early lactation

The objective of this study was to determine the effects of milk fat depression induced by supplementing conjugated linoleic acid (CLA; trans-10,cis-12 and cis-9,trans-11 CLA) or feeding a higher starch and oil-containing diet (HSO) on metabolic changes in dairy cows after calving. The main hypothesis was that the 2 strategies to decrease milk fat yield could have different effects on performance, energy balance (EB), and inflammatory status in early lactation. Thirty-three Nordic Red dairy cows were used in a randomized block design from 1 to 112 d of lactation and fed one of the following treatments: control (CON), CLA-supplemented diet, or HSO diet. Dry matter intake and milk yield were measured daily whereas milk composition was measured weekly throughout the experiment. Nutrient digestibility, EB, and plasma hormones and metabolites were measured at 3, 7, 11, and 15 wk of lactation in respiration chambers. The HSO diet led to lower intakes of dry matter, neutral detergent fiber, and gross energy compared with CON and CLA diets. The CLA diet and especially the HSO diet resulted in lower energy-corrected milk yield during the first 7 wk of lactation than those fed CON. The EB was numerically higher for HSO and CLA diets compared with CON at wk 3 and 7. Plasma glucose concentration was higher by the CLA diet at wk 3 and by the HSO diet from wk 3 to 15 compared with CON. Plasma nonesterified fatty acids were higher at wk 3 in the CON group (indicating more lipid mobilization) but decreased thereafter to similar levels with the other groups. The HSO-fed cows had higher plasma ceruloplasmin, paraoxonase, and total bilirubin concentrations in the entire experiment and showed the highest levels of reactive oxygen metabolites. These results suggest an increased inflammatory and oxidative stress state in the HSO cows and probably different regulation of the innate immune system. This study provides evidence that milk fat depression induced by feeding HSO (as well as CLA) decreased milk fat secretion and improved EB compared with CON in early lactation. The increase in plasma glucose and paraoxonase levels with the HSO diet may imply a better ability of the liver to cope with the metabolic demand after parturition. However, the negative effect of HSO on feed intake, and the indication of increased inflammatory and oxidative stress warrant further studies before the HSO feeding strategy could be supported as an alternative to improve EB in early lactation.

Effects of supplementing pomegranate peel with fatty acid sources on oxidative stress, blood metabolites, and milk production of dairy cows fed high-concentrate diets

Primiparous cows are more susceptible to oxidative stress than multiparous cows because of their lower total antioxidant capacity. The objective of this study was to evaluate the effects of fatty acid (FA) source with and without pomegranate peel (PP) as an antioxidant-rich source in the diet on oxidative stress, blood metabolites, lactation performance, and nutrient digestibility in primiparous lactating cows. Twelve Holstein dairy cows in early lactation were randomly assigned to a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Each period lasted 28 days with 21 days for feed adjustment and 7 days for data and sample collection. The diets were supplemented with 15 g/kg DM of palmitic acid-enriched fat (enriched in saturated FA) or fish oil (enriched in unsaturated FA) contained 0 or 87 g/kg DM of PP. Pomegranate peels increased total dietary antioxidant concentrations and fish oil reduced the ratio of n-6 to n-3 in the experimental diets. Significant interactions were observed for plasma non-esterified FA and malondialdehyde concentrations, milk fat yield, and apparent total-tract nutrient digestibility. Plasma non-esterified FA concentrations decreased in cows fed palmitic acid-enriched fat when PP was included in the diet. Diets with PP resulted in increased plasma concentrations of malondialdehyde in cows fed fish oil but not in those fed the palmitic acid-enriched fat. In addition, total plasma antioxidant capacity increased in cows fed PP containing diets, whereas blood inflammatory markers were not affected by the by inclusion of PP. Supplementing palmitic acid-enriched fat increased milk fat yield by 10% compared with fish oil, whereas a trend toward a decrease in this variable was observed when fish oil was fed without PP. Also, feed intake increased and milk protein concentration decreased in cows consuming diets containing PP, while milk yield was greater for cows fed fish oil. Cows fed palmitic acid-enriched fat had lower DM and NDF digestibility than in those fed fish oil. The molar fraction of propionate in the rumen decreased and the ratio of acetate to propionate increased in cows fed PP containing diets. Cows fed palmitic acid-enriched fat had a greater molar fraction of propionate but a lower ratio of acetate to propionate than cows fed fish oil. Overall, inclusion of PP in diets containing fish oil or palmitic acid-enriched fat contributed to improved feed intake and antioxidant capacity, while we observed no interaction on oxidative stress and inflammatory markers in dairy cows.

Role of Hydrogen Sulfide and Polysulfides in the Regulation of Lipolysis in the Adipose Tissue: Possible Implications for the Pathogenesis of Metabolic Syndrome.

Hydrogen sulfide (H2S) and inorganic polysulfides are important signaling molecules; however, little is known about their role in the adipose tissue. We examined the effect of H2S and polysulfides on adipose tissue lipolysis. H2S and polysulfide production by mesenteric adipose tissue explants in rats was measured. The effect of Na2S and Na2S4, the H2S and polysulfide donors, respectively, on lipolysis markers, plasma non-esterified fatty acids (NEFA) and glycerol, was examined. Na2S but not Na2S4 increased plasma NEFA and glycerol in a time- and dose-dependent manner. Na2S increased cyclic AMP but not cyclic GMP concentration in the adipose tissue. The effect of Na2S on NEFA and glycerol was abolished by the specific inhibitor of protein kinase A, KT5720. The effect of Na2S on lipolysis was not abolished by propranolol, suggesting no involvement of β-adrenergic receptors. In addition, Na2S had no effect on phosphodiesterase activity in the adipose tissue. Obesity induced by feeding rats a highly palatable diet for 1 month was associated with increased plasma NEFA and glycerol concentrations, as well as greater H2S production in the adipose tissue. In conclusion, H2S stimulates lipolysis and may contribute to the enhanced lipolysis associated with obesity.

Leptin Concentration, Obesity, and Plasma Non-esterified Fatty Acid Levels in Children.

The association between obesity and higher non-esterified fatty acid (NEFA) levels has been established in adults. In contrast, lower NEFA levels have been described in children with obesity although the reason behind this association remains unclear. Leptin, which regulates body weight and plays a role in lipolysis, could be involved in this relationship. We evaluated the influence of leptin in the association between obesity and NEFA concentrations in children, analyzing two cohorts including 684 6- to 8-year-olds and 836 12- to 16-year-old children, respectively. After adjusting by leptin, insulin levels remained significantly higher in adolescents with obesity as compared with levels in those without obesity. However, insulin levels showed no differences between prepubertal children with and without obesity. The significantly lower NEFA concentrations observed in 6- to 8-year-old girls with obesity disappeared when comparing NEFA levels between girls with and without obesity after adjusting by leptin. We report an influence of leptin levels on the association between obesity and insulin and NEFA in young children that is not observed in adolescents. Our findings add information about factors that may contribute to explain the lower NEFA levels described in prepubertal children with obesity.

Role of Corticosterone in Lipid Metabolism in Broiler Chick White Adipose Tissue.

Excessive accumulation of body fat in broiler chickens has become a serious problem in the poultry industry. However, the molecular mechanism of triglyceride accumulation in chicken white adipose tissue (WAT) has not been elucidated. In the present study, we investigated the physiological importance of the catabolic hormone corticosterone, the major glucocorticoid in chickens, in the regulation of chicken WAT lipid metabolism. We first examined the effects of fasting on the mRNA levels of lipid metabolism-related genes associated with WAT, plasma corticosterone, and non-esterified fatty acid (NEFA). We then examined the effects of corticosterone on the expression of these genes in vivo and in vitro. In 10-day-old chicks, 3 h of fasting significantly decreased mRNA levels of lipoprotein lipase (LPL) in WAT and significantly elevated plasma concentrations of NEFA. Six hours of fasting significantly increased mRNA levels of adipose triglyceride lipase (ATGL) in WAT and significantly elevated plasma concentrations of corticosterone. On the other hand, fasting significantly reduced mRNA levels of LPL in WAT and elevated plasma concentrations of NEFA in 29-day-old chicks without affecting mRNA levels of ATGL in WAT or plasma corticosterone concentrations. Oral administration of corticosterone significantly reduced mRNA levels of LPL and significantly increased the mRNA levels of ATGL in WAT in 29-day-old chicks without affecting plasma NEFA concentrations. The addition of corticosterone to primary chicken adipocytes significantly increased mRNA levels of ATGL, whereas mRNA levels of LPL tended to decrease. NEFA concentrations in the culture medium were not influenced by corticosterone levels. These results suggest that plasma corticosterone partly regulates the gene expression of lipid metabolism-related genes in chicken WAT and this regulation is different from the acute elevation of plasma NEFA due to short-term fasting.

Co-Morbidly of Malaria and Typhoid Perturbs Lipid Homeostasis in Humans

Introduction: Malaria and typhoid diseases have remained endemic in low-income countries, including Nigeria. Aims: This study investigated the impact of malaria concurrently occurring with typhoid on plasma, erythrocytes, and lipoproteins lipid profile. Materials and Methods: Cholesterol, triacylglycerol (TAG) phospholipids (PLs), and non-esterified fatty acids (NEFAs) were determined spectrophotometrically in controls and patients presenting at the Out-Patient Clinic of the State Hospital, Abeokuta, Nigeria. Results: The presence of either or both parasitic infections provoked dyslipidaemia when compared with the controls. Dyslipidaemia was characterised by significant (P &lt; 0.05) decreased plasma, erythrocytes, high density lipoprotein (HDL), and low density lipoprotein (LDL) cholesterol; however very LDL (VLDL) cholesterol increased. While hypertriglyceridemia was observed in plasma, hypotriglyceridemia was observed in the erythrocytes of the patients. In HDL, hypertriglyceridemia was observed in malaria-infected patients whereas hypotriglyceridemia was observed in typhoid-infected and co-infection subjects. Malaria and/or typhoid induced phospholipidaemia in plasma and erythrocytes, but provoked decreased HDL-phospholipids (PLs) only in malaria-infected patients. Malaria and/or typhoid elicited decreased LDL+VLDL-PLs. While increased plasma NEFAs concentration was observed in malaria-infected patients; malaria and co-infection resulted in decreased erythrocytes NEFAs. Malaria and/or typhoid caused decreased cholesterol/phospholipids molar ratio in plasma, erythrocytes, and HDL. Conclusion: The findings of this study indicate that parasitic protozoa and bacterial infections produce a plethora of effects on lipid metabolism, ranging from up-/down-regulation of certain lipid metabolites. These may be early biochemical events in the induction of atherosclerosis by parasitic infections.

Early Warning for Ovarian Diseases Based on Plasma Non-esterified Fatty Acid and Calcium Concentrations in Dairy Cows.

Inactive ovaries (IO) and ovarian (follicular or luteal) cysts (FC or LC) are two common ovarian diseases leading to infertility in dairy cattle. Both disorders are associated with altered metabolites and hormones. There are currently no known effective biomarkers that can be used for early diagnosis of ovarian diseases. The purpose of this study was to identify the plasma biomarkers of ovarian diseases in Holstein dairy cows that facilitate an early diagnosis of the diseases and control its progression. The experiment was performed from 3 weeks postpartum and last for 7 weeks. Seventy-six multiparous Holstein cows (mean age, 4.36 years; weight, 635.63 kg) were divided into healthy control group (HC, n = 22), FC group (n = 18), LC group (n = 18) and IO group (n = 18) by rectal palpation or ultrasonography during the last 2 weeks before trial end. Blood was collected via tail vein for measurement of plasma energy metabolites, liver function indicators, minerals, and hormones at 3 and 8 weeks postpartum. Data were analyzed by Mann-Whitney U, Kruskal-Wallis, Spearman correlation, binary logistic regression analysis and receiver operating characteristic analysis, where applicable. At 8 weeks postpartum, FC cows had a more severe body condition score loss and these had greater levels of non-esterified fatty acids (NEFA) and estradiol, and lesser levels of alanine aminotransferase (ALT), progesterone and insulin-like growth factor 1 (IGF-1) levels than HC cows (P < 0.05). LC cows had a lower milk yield, higher NEFA and progesterone levels, and lower calcium, phosphorus and magnesium levels than HC cows (P < 0.05). IO cows had a lower body condition score, higher NEFA levels, and lower ALT, calcium, phosphorus, magnesium, estradiol, progesterone and IGF-1 levels than HC cows (P < 0.05). At 3 weeks postpartum, cows with ovarian diseases had greater (P < 0.05) concentrations of NEFA, and lesser concentrations of ALT, calcium, phosphorus and IGF-1 than HC cows. Early warning values for ovarian diseases were plasma NEFA concentrations >0.50 mmol/L, or calcium concentrations <2.02 mmol/L. Therefore, plasma NEFA and calcium could be used as early-warning indicators for ovarian diseases in dairy cows.

Metabolic and production parameters of dairy cows with different dry period lengths and parities.

To assess the effects of dry period (DP) length on metabolic, reproductive, and productive parameters, second- (SP) and third- (TP) parity cows were assigned to a traditional (9 weeks, T) or short (5 weeks, S) DP, obtaining four subgroups: second-parity cows with traditional (SPT = 8) and short (SPS = 8) DP, third-parity cows with traditional (TPT = 8) and short (TPS = 10) DP. Plasma insulin-like growth factor-I (IGF-I) and non-esterified fatty acid (NEFA) levels were assessed from 5 weeks before to 14 weeks after parturition. IGF-I concentrations were affected by parity (P < 0.05) and by the interaction of time and DP length (P < 0.01). NEFA levels were affected only by time (P < 0.01). S DP cows showed a shorter interval between calving and ovarian cyclicity resumption (P < 0.01) and a higher milk yield (P < 0.01) and fat and protein corrected milk (P < 0.01) compared with T DP cows. Decreased milk protein content was found in the SPS group compared to the SPT (P < 0.05) and the TPS (P < 0.05) group. In conclusion, a short DP length does not affect reproductive performances, except for hastening the resumption of ovarian cyclicity. A short DP appears to increase milk production and is associated with higher IGF-I levels both in the prepartum and the postpartum period.

Mechanistic studies of PEG-asparaginase-induced liver injury and hepatic steatosis in mice

PEGylated-l-asparaginase (PEG-ASNase) is a chemotherapeutic agent used to treat pediatric acute lymphoblastic leukemia (ALL). Its use is avoided in adults due to its high risk of liver injury including hepatic steatosis, with obesity and older age considered risk factors of the injury. Our study aims to elucidate the mechanism of PEG-ASNase-induced liver injury. Mice received 1500 U/kg of PEG-ASNase and were sacrificed 1, 3, 5, and 7 days after drug administration. Liver triglycerides were quantified, and plasma bilirubin, ALT, AST, and non-esterified fatty acids (NEFA) were measured. The mRNA and protein levels of genes involved in hepatic fatty acid synthesis, β-oxidation, very low-density lipoprotein (VLDL) secretion, and white adipose tissue (WAT) lipolysis were determined. Mice developed hepatic steatosis after PEG-ASNase, which associated with increases in bilirubin, ALT, and AST. The hepatic genes Ppara, Lcad/Mcad, Hadhb, Apob100, and Mttp were upregulated, and Srebp-1c and Fas were downregulated after PEG-ASNase. Increased plasma NEFA, WAT loss, and adipose tissue lipolysis were also observed after PEG-ASNase. Furthermore, we found that PEG-ASNase-induced liver injury was exacerbated in obese and aged mice, consistent with clinical studies of ASNase-induced liver injury. Our data suggest that PEG-ASNase-induced liver injury is due to drug-induced lipolysis and lipid redistribution to the liver.

Effects of endocannabinoids on feed intake, stress response and whole-body energy metabolism in dairy cows

Endocannabinoids, particularly anandamide (AEA) and 2-arachidonoylglycerol (2-AG), are instrumental in regulating energy homeostasis and stress response. However, little is known about the endocannabinoid system (ECS) in ruminants, although EC could improve dairy health and productivity, at least by increasing feed intake. In this study, we report if intraperitoneal (i.p.) AEA and 2-AG administration affects feed intake, whole-body macronutrient metabolism, isolation and restraint stress, and whether diet composition modulates circulating endocannabinoid concentrations in cows. Twenty Simmental cows in late lactation were fed a grass silage and a corn silage based diet. On each diet, cows received daily i.p. injections with either AEA (5 µg/kg; n = 7), 2-AG (2.5 µg/kg; n = 6) or saline (n = 7) for 8 days. Endocannabinoid administration for 5 days under free-ranging (non-stressed) conditions had no effect on feed intake or energy balance, but attenuated the stress-induced suppression of feed intake when housing changed to individual tie-stalls without social or tactile interaction. Endocannabinoids increased whole-body carbohydrate oxidation, reduced fat oxidation, and affected plasma non-esterified fatty acid concentrations and fatty acid contents of total lipids. There was no effect of endocannabinoids on plasma triglyceride concentrations or hepatic lipogenesis. Plasma AEA concentrations were not affected by diet, however, plasma 2-AG concentrations tended to be lower on the corn silage based diet. In conclusion, endocannabinoids attenuate stress-induced hypophagia, increase short-term feed intake and whole-body carbohydrate oxidation and decrease whole-body fat oxidation in cows.

NEFA Promotes Autophagosome Formation through Modulating PERK Signaling Pathway in Bovine Hepatocytes.

Simple SummaryNegative energy balance can lead to the mobilization of large amounts of body fat. A large amount of non-esterified fatty acids (NEFA) produced by lipolysis not only can be used for energy generation by β-oxidation in the liver but can also act as a potential regulator of lipid metabolism. The present study provides evidence that NEFA can activate hepatocyte autophagy through the protein kinase R-like endoplasmic reticulum kinase (PERK) signaling pathway. Autophagy has been reported to contribute to lipid metabolism through promoting the breakdown of intracellular lipids. These findings enable a better understanding of the redistribution and utilization of energy during the perinatal period of dairy cows.During the perinatal period, the abnormally high plasma non-esterified fatty acids (NEFA) concentration caused by the negative energy balance (NEB) can impose a significant metabolic stress on the liver of dairy cows. Endoplasmic reticulum (ER) stress is an important adaptive response that can serve to maintain cell homeostasis in the event of stress. The protein kinase R-like endoplasmic reticulum kinase (PERK) pathway is the most rapidly activated cascade when ER stress occurs in cells and has an important impact on the regulation of hepatic lipid metabolism and autophagy modulation. However, it is unknown whether NEFA can affect autophagy through modulating the PERK pathway, under NEB conditions. In this study, we provide evidence that NEFA treatment markedly increased lipid accumulation, the phosphorylation level of PERK and eukaryotic initiation factor 2α (eIF2α), and the expression of glucose-regulated protein 78 (Grp78), activating transcription factor 4 (ATF4), and C/EBP homologous protein (CHOP). More importantly, NEFA treatment can cause a substantial increase in the protein levels of autophagy-related gene 7 (ATG7), Beclin-1 (BECN1), sequestosome-1 (p62), and microtubule-associated protein 1 light chain 3 (LC3)-II, and in the number of autophagosomes in primary bovine hepatocytes. The addition of GSK2656157 (PERK phosphorylation inhibitor) can significantly inhibit the effect of NEFA on autophagy and can further increase lipid accumulation. Overall, our results indicate that NEFA could promote autophagy via the PERK pathway in bovine hepatocytes. These findings provide novel evidence about the potential role of the PERK signaling pathway in maintaining bovine hepatocyte homeostasis.

Effect of Boron Supplementation on Nutrient Utilization and Productive Performance of Peripartum Murrah Buffaloes.

Boron (B) has been established as a beneficial micronutrient for some farm animals. However, its impact on coping negative energy balance during transition and subsequent production performance needs critical perusal. Therefore, the present study was undertaken to determine the effect of B supplementation on productive performance, apparent nitrogen (N), and mineral utilization in peripartum Murrah buffaloes. Thirty advanced pregnant buffaloes (60days prior to expected date of calving) were allocated into three groups, i.e. control, B-200, and B-400, and supplemented with pharmacological concentration of B at 0, 200, and 400ppm, respectively, from 45days prior to expected date of calving till 120days post calving. Two metabolism trials were conducted (with animals having similar expected date of calving), one during prepartum (30days prior to the expected date of calving) and another during postpartum (90days post calving) phase to evaluate nutrient utilization and balance of N as well as minerals. Results revealed that B supplementation decreased (P < 0.05) overall plasma nonesterified fatty acids (NEFA), whereas plasma level of β-hydroxybutyric acid, insulin, triglyceride, and glucose did not differ (P > 0.05) among the groups. Dry matter intake, nutrient digestibility, and N balance remained unaffected with B supplementation. Higher (P < 0.05) apparent absorption coefficient for magnesium (Mg) and zinc (Zn) was observed in pregnant animals, while during lactation, absorption coefficient of calcium, Mg, and Zn was increased (P < 0.05) in B-supplemented groups. Hence, it can be concluded that alteration in NEFA concentration and variation in apparent absorption coefficient of minerals with B supplementation suggest its role in energy and mineral metabolism. However, further investigations are required to determine the underlying mechanism of action for the present findings.

Changes in plasma electrolytes, minerals, and hepatic markers of health across the transition period in dairy cows divergent in genetic merit for fertility traits and postpartum anovulatory intervals

Peripartum metabolism and subsequent reproductive performance of dairy cows are linked, with maladaptation over the transition period associated with poor reproductive success. A herd of seasonal calving, grazing dairy cows was established that differed in their genetic merit for fertility traits. The heifers were produced by a customized mating program to achieve a 10-percentage point divergence in the New Zealand fertility breeding value (FertBV) as follows: +5 FertBV (POS) versus -5% FertBV (NEG), while also limiting divergence in other breeding values, including body weight, body condition score, and milk production. In this study, we aimed to characterize differences in metabolic, mineral, and metabolic stress marker profiles during their first postpartum transition period as primiparous heifers and to examine if animals with longer postpartum anestrous intervals (PPAI; more than 66 d compared with less than 35 d) had greater metabolic dysfunction. Blood was sampled at -21, -14, -7, 0, 4, 7, 10, 14, 17, 21, 28, and 35 d relative to calving in 455 primiparous cows and plasma analyzed. The NEG cows had lower concentrations of both plasma nonesterified fatty acids and β-hydroxybutyrate at d 7 compared with POS cows. Detailed temporal profiling of various metabolic, mineral, and metabolic stress markers was undertaken in a subset of cows (n = 70). Cows were selected retrospectively to create 4 groups in a 2 × 2 factorial design with either a POS or NEG FertBV and either a short (19-35 d) or long (66-131 d) PPAI. The NEG cows tended, on average, to have lower nonesterified fatty acids and β-hydroxybutyrate concentrations compared with POS cows across the transition period. Mean body weight and body condition score was greatest in NEG cows when compared with the POS cows and an interaction with day demonstrated this only occurred precalving. They also had indications of improved liver health precalving, with higher albumin-to-globulin ratios and lower bilirubin concentrations. Concentrations of aspartate aminotransferase were lower, and the Na-to-Cl ratio was greater in cows with a long versus a short PPAI at d 28 and d 35 after calving, potentially because of cows with a short PPAI (19-35 d) returning to estrous during this time. Magnesium concentrations were lower in NEG cows with a short PPAI from d 21 onwards, indicating NEG cows may metabolically respond to estrous differently than POS cows. The NEG-long PPAI cows had greater gamma-glutamyl transferase concentrations from calving until d 28 and lower bilirubin concentrations throughout the transition period. Together, the results demonstrate significant effects of FertBV on peripartum metabolic status. However, most of the markers tested returned to reference intervals within 4 d after calving or remained within those intervals for the whole transition period, indicating relatively minor biological effects of FertBV on transition period adaptation. The profound differences in reproductive performance among the groups was not explained by underlying differences in metabolic responses during the transition period.

Revisiting the Relationships between Fat-to-Protein Ratio in Milk and Energy Balance in Dairy Cows of Different Parities, and at Different Stages of Lactation.

Simple SummaryData from 840 Holstein-Friesian cows (1321 lactations) were used to evaluate trends in fat-to-protein ratios in milk (FPR), and the use of FPR as an indicator of energy balance (EB). The fat-to-protein ratio was negatively related to EB, and this relationship became more negative with increased parity. Regression slopes describing linear relationships between FPR and EB differed over time, although trends were inconsistent. Similarly, ‘High’ FPR scores in milk (≥1.5) were consistently associated with a greater negative energy balance, milk yields, body weight loss, and plasma non-esterified fatty acid concentrations; however, their relationships with dry matter intake did not follow a clear trend. Although FPR can provide an indication of EB at a herd level, this analysis suggests that FPR cannot accurately predict the EB of individual cows. A statistical re-assessment of aggregated individual cow data was conducted to examine trends in fat-to-protein ratio in milk (FPR), and relationships between FPR and energy balance (EB, MJ of ME/day) in Holstein-Friesian dairy cows of different parities, and at different stages of lactation. The data were collected from 27 long-term production trials conducted between 1996 and 2016 at the Agri-Food and Biosciences Institute (AFBI) in Hillsborough, Northern Ireland. In total, 1321 lactations (1 to 20 weeks in milk; WIM), derived from 840 individual cows fed mainly grass silage-based diets, were included in the analysis. The energy balance was calculated daily and then averaged weekly for statistical analyses. Data were further split in 4 wk. intervals, namely, 1–4, 5–8, 9–12, 13–16, and 17–20 WIM, and both partial correlations and linear regressions (mixed models) established between the mean FPR and EB during these periods. Three FPR score categories (‘Low’ FPR, <1.0; ‘Normal’ FPR, 1.0–1.5; ‘High’ FPR, >1.5) were adopted and the performance and EB indicators within each category were compared. As expected, multiparous cows experienced a greater negative EB compared to primiparous cows, due to their higher milk production relative to DMI. Relatively minor differences in milk fat and protein content resulted in large differences in FPR curves. Second lactation cows displayed the lowest weekly FPR, and this trend was aligned with smaller BW losses and lower concentrations of non-esterified fatty acids (NEFA) until at least 8 WIM. Partial correlations between FPR and EB were negative, and ‘greatest’ in early lactation (1–4 WIM; r = −0.38 on average), and gradually decreased as lactation progressed across all parities (17–20 WIM; r = −0.14 on average). With increasing parity, daily EB values tended to become more negative per unit of FPR. In primiparous cows, regression slopes between FPR and EB differed between 1–4 and 5–8 WIM (−54.6 vs. −47.5 MJ of ME/day), while differences in second lactation cows tended towards significance (−57.2 vs. −64.4 MJ of ME/day). Irrespective of the lactation number, after 9–12 WIM, there was a consistent trend for the slope of the linear relationships between FPR and EB to decrease as lactation progressed, with this likely reflecting the decreasing milk nutrient demands of the growing calf. The incidence of ‘High’ FPR scores was greatest during 1–4 WIM, and decreased as lactation progressed. ‘High’ FPR scores were associated with increased energy-corrected milk (ECM) yields across all parities and stages of lactation, and with smaller BW gains and increasing concentrations (log transformed) of blood metabolites (non-esterified fatty acid, NEFA; beta-hydroxybutyrate, BHB) until 8 WIM. Results from the present study highlight the strong relationships between FPR in milk, physiological changes, and EB profiles during early lactation. However, while FPR can provide an indication of EB at a herd level, the large cow-to-cow variation indicates that FPR cannot be used as a robust indicator of EB at an individual cow level.